Powered air-purifying respirator management system

ABSTRACT

The present invention relates to a particular type of fan-forced positive pressure breathing apparatus, commonly known as Powered Air-Purifying Respirators (PAPRs). In particular the invention concerns monitoring the operation of such equipment. In a first aspect, the invention provides a powered air-purifying respirator which includes data collection means to enable the volume of air drawn through the filter to be determined. In another aspect, the invention comprises a management system for monitoring and analyzing operational data from at least one powered air-purifying respirator. The management system includes data collection means associated with each respirator to enable the volume of air drawn through that respirator&#39;s filter to be determined, and electronic data processing apparatus into which the data collected by the data collection means is uploaded for analysis. The data processing apparatus may be partly situated on-board each respirator in order to enable alarms to be given to the wearers at appropriate times. However, a remote computer system having data processing facilities will be able to store and subsequently display the data collected, as well as enabling more sophisticated analysis.

FIELD OF THE INVENTION

The present invention relates to a particular type of fan-forcedpositive pressure breathing apparatus, commonly known as PoweredAir-Purifying Respirators (PAPRs). In particular the invention concernsmonitoring the operation of such equipment.

BACKGROUND ART

Non-powered air-purifying respirator equipment involves a breathing maskhaving a filtered air inlet. Air is drawn through the filter by means ofthe wearer's breathing action. A considerable problem with this type ofrespirator is how to determine when the filter is due to be replaced. Anumber of "end-of-service-life" indicators have been proposed over theyears, but none have been widely adopted. The major difficulty is thatthe useful life of the filter is determined by several non-relatedfactors, such as the proportion of contaminant in the atmosphere, thehumidity and the effort required of the user. Present estimates offilter lifetime are based on a number of such factors, and it takesconsiderable experience to weigh them together.

In recent years positive air-pressure respirators have been introduced,and these employ a pump which draws ambient air in through a filter andsupply it to the face mask. The pump comprises a motorized fan whichdraws air through the filter in proportion to the speed of revolution.In such simple motorized equipment the filter life, in a particularenvironment, is directly related to the operating time and in practicecan be estimated with reasonable reliability. However, these respiratorssuffer from the problems that they do not necessarily provide sufficientair flow for periods of maximum inhalation, but are otherwise wastefulin filter usage by providing excess flow during exhalation cycles.

A new generation of powered air-purifying respirators (PAPRs) that hasbeen developed by the applicant employs a breathing demand valve toovercome the deficiencies of the simple positive air-pressurerespirators mentioned above. However, the inclusion of the demand valvehas reintroduced the unpredictable variant of air consumption into thedetermination of filter life.

DISCLOSURE OF THE INVENTION

In a first aspect, the invention provides a powered air-purifyingrespirator comprising: a face-piece to cover at least the mouth or noseof a wearer; a pump unit to supply ambient air to the face-piece via anair passage; a decontaminating means to filter the ambient air suppliedto the face-piece; and a demand valve associated with the face-piece andresponsive to a wearer's demand for air to deliver supplied air to thewearer. The respirator further includes data collection means to enablethe volume of air drawn through the decontaminating means to bedetermined. This equipment takes advantage of the fact that the poweredrespirator has on-board power available to drive the data collectionmeans.

The phrase "decontaminating means" has been used generically to indicateany means which is able to decontaminate the air for the wearer. Thedecontaminating means has been described with reference to a "filter"when that word has been used in a broad functional sense. It should beappreciated that the word "filter" also has a jargon meaning in thisfield to refer to a device for the mechanical removal of particles fromthe air; a filter usually comprises a fine mesh that will let air passbut not particles. The phrase "decontaminating means" also includeswithin its scope:

absorbers which suck up contaminants, like a sponge;

adsorbers to the surface of which contaminants adhere, for examplecarbon based gas filters; and

catalysts which transform a contaminant into a different materialthrough a chemical reaction, for example "carbon monoxide filters".

The phrase "face-piece" has been used generically to indicate anyapparatus which covers at least the mouth or nose of a wearer, and itincludes a mask, hood or headpiece.

The data collection means may comprise a flow meter to measure theinstantaneous flow of air within the respirator, and a clock. The flowmeter and clock are operable to form an accumulating volume meter,enabling the total volume of air drawn through the decontaminating meansto be determined. The flow meter can be situated anywhere in the airpassage where a true flow value may be measured.

The actual determination of the volume of air drawn through thedecontaminating means need not be conducted on-board the respirator, butif the determination is made on-board, then an alarm can conveniently beprovided to the wearer when the decontaminating means nears the end ofits useful life.

Whether the volume is determined on-board the respirator, or not, itwill be advantageous to include a data port to enable either the rawdata measured by the measuring means, or the volume data determined, tobe uploaded to a remote computer system. The computer system may includea database containing information about many respirants and enable anadministrator to closely observe their operation and performance. Thismay also enable the administrator to ensure the wearers are operatingthe respirators in a safe fashion.

An additional feature is to associate identification marks with eachrespirator, or with some or all components of each respirator, in orderto permit logging of those identifications into the database. Theidentification marks will generally comprise unique indicia and mayinvolve the use of techniques such as barcodes or magnetic coded strips.

Identity coding of each decontaminating means enables the performancecharacteristics of each type to be analyzed. The analysis may considerdata such as the types and concentrations of contaminants, the humidity,the temperature, the periods of use, the flow resistance and the maximumair flow rate through the decontaminating means. From such analysis itis possible to predict the optimum life of a particular type ofdecontaminating means in any particular application or environment.

On-board power will usually be provided to the respirator byrechargeable batteries. Operational data, such as battery voltage, mayalso be measured on-board. An alarm signal may then be sent to thewearer in advance of discharge. More sophisticated systems may monitorthe time since the last recharging and the operational time of eachbattery, using its identification, to predict battery failure inadvance. An alarm could then be displayed at the time of collection ofthe respirator or at the time of return, to ensure recharging beforeuse. Where a stack of batteries are used each individual cell may bemonitored, which is useful as the performance of a battery is limited bythe performance of the weaker cell in a stack.

Alarms to the wearer may be provided in the form of a displayed message,an audible tone, a warning light or combinations of these. The alarm maybe issued as a simple signal or as a more complex sequence of warnings.Flashing lights, intensity modulations or color shift may be used toindicate different levels of seriousness of the alarm. Fail-safeoperation of the alarm may also be included in the alarm scheme.

Air flow measurement may be made by an air flow restrictor such as anorifice plate or mesh and a pressure sensor adapted to measure thechange in pressure across the restrictor. Alternatively, the air flowrestrictor may comprise an air transfer hose, and the air flow may bemeasured by a pressure sensor adapted to measure the change in pressurebetween the pump unit and the face-piece. In another alternative, airflow measurement may be made by an ultrasound transmitter and receiverarranged to transmit and detect ultrasound travelling along a portion ofthe air transfer channel. The flow rate in this case is directlyproportional to the time shift of the ultrasound travelling along thechannel. This method has the advantage that it places no flowrestriction in the air flow. In another alternative, flow measurementmay be made by a heated thermistor placed in a stream of air: flow rateis then proportional to the cooling effect on the thermister.

Pressure may be measured by a silicon pressure transducer. In analternative, pressure may be measured by a flexible membrane arranged toflex with changes in pressure, and an ultrasound detection system. Thedetection system may involve an ultrasound transmitter arranged todirect ultrasound at the membrane, an ultrasound receiver arranged todetect ultrasound reflected from the membrane and an analyzer capable ofdetermining the change in transit time of the transmitted and receivedsignals. The changes in transit time may be calibrated to provide anindication of air pressure. To compensate for changes in the transittime of the ultrasound caused by temperature variations, temperatureprobes may also be provided in both flow and pressure sensing systems.

In another aspect, the invention comprises a management system formonitoring and analyzing operational data from at least one poweredair-purifying respirator of the type comprising: a face-piece to coverat least the mouth and nose of a wearer: a pump unit to supply ambientair to the face-piece via an air passage; a decontaminating means tofilter the ambient air supplied to the face-piece: and a demand valveassociated with the face-piece and responsive to a wearer's demand forair to deliver supplied air to the wearer. The management systemincludes data collection means associated with each respirator to enablethe volume of air drawn through that respirator's decontaminating meansto be determined, and electronic data processing apparatus into whichthe data collected by the data collection means is uploaded foranalysis. The data processing apparatus may be partly situated on-boardeach respirator in order to enable alarms to be given to the wearers atappropriate times. However, a remote computer system having dataprocessing facilities will be able to store the data in a database andsubsequently display the data collected as well as enabling moresophisticated analysis.

The respirators, and some or all of their component parts, may beidentified in order to enable the management system to log data aboutthe operation of the various components. From the information themanagement system may provide other warnings, such as imminent batteryfailure, as well as performance analysis.

BRIEF DESCRIPTION OF THE DRAWINGS

An example of the invention will now be described with reference to theschematic arrangement of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A powered air-purifying respirator is generally shown at 1. Therespirator includes a pump unit 2, and a face-piece 3 comprising a maskwhich is adapted to cover the nose and mouth of a wearer, and isadjustable to fit snugly to the contours of the wearer's face. The pumpunit 2 and mask 3 are interconnected by an air passage defined byflexible hose 4. A demand valve 5 is positioned at the point where theflexible hose 4 enters the mask 3. The demand valve 5 delivers air tothe mask according to the wearer's instantaneous requirements from thepressurized supply in tube 4. A filter 6 is positioned at the air inletof pump unit 2. In use ambient air is drawn through filter 6 at the airinlet and supplied to mask 3 through hose 4.

Inside pump unit 2 is a centrifugal fan 7 and an electronic motor 8 todrive the fan 7. A rechargeable battery 9 provides electrical power tothe respirator. In addition to driving motor 8, battery 9 provideselectrical power to a flow meter 10 positioned at or within flexiblepipe 4, a pressure sensor 11 in mask 3, a second pressure sensor 12positioned in the air inlet behind filter 6 and a third pressure sensor13 located at the outlet of the fan. In addition battery 9 supplieselectrical power to a warning light 14 in mask 3, and an audible buzzer15 in pump unit 2.

The pump unit 2 also includes data collection electronics 16 whichreceives inputs from motor 8, battery 9, flow meter 10 and pressuresensors 11, 12 and 13. The collected data may be time stamped every timea record is logged. Data processing logic within the data collectionmodule 16 responds to the inputs to provide warnings to the wearer. Inparticular, electronics 16 measures the instantaneous flow of filteredair through pipe 4, and this is combined with a measurement of the timeduring which the respirator has been in use to determine the volume ofair that has passed through filter 6. This information can be used toprovide an alarm when the filter nears or reaches the end of its workinglife. The alarm is visual by light 14 and audible by buzzer 15.

The electronics 16 also monitors the battery 9 voltage, and warns theuser of impending battery failure by light 14 and buzzer 15. The batterycan then be recharged by recharger 17.

Data logged by the electronics 16 is periodically uploaded to a databasein a remote computer system 18 to enable storage and further analysis ofthe data logged. Uploading the data provides a mechanism for systemmanagement.

The remote computer system receives not only operational data from theflow meter and sensors, but also data concerning alarm events. A systemadministrator will enter the identity code of each component as eachrespirator is assembled. This information may be marked with a barcodelabel on each component. He will also enter the environmentalinformation, such as the type of contaminant, the degree ofcontamination, the humidity and the temperature, each day or asregularly as required. This information allows not only monitoring ofthe operational history and performance of each component, but alsoprovides a facility for predicting failure modes. Such prediction can beused to create service regimes and component replacement schedules. Theadministrator will ensure that the components are changed at the timesrequired, and that the new component identities are entered.

Most importantly this information is used to calculate the precise timeat which the filters require replacing. A suitable margin may be addedand a signal sent to the system administrator or the wearer when afilter requires replacing.

Although the invention has been described with reference to a particularembodiment, it should be appreciated that it may be embodied in manyother forms. For instance the face-mask is not essential and theinvention may be applied to any other form of respirator. The componentsneed not be barcoded, and any other convenient identification scheme maybe adapted. Further, the management system may also provide otherwarnings such as motor and fan service intervals, and it may providereminders to upload data. In another variant the demand valve 5 may bepositioned at the pump unit, and the filter may be positioned at theoutlet of the pump. It should also be appreciated that any suitable typeof pump could replace the centrifugal pump illustrated.

It will be appreciated by persons skilled in the art that numerousvariations and/or modifications may be made to the invention as shown inthe specific embodiments without departing from the spirit or scope ofthe invention as broadly described. The present embodiments are,therefore, to be considered in all respects as illustrative and notrestrictive.

We claim:
 1. A powered air-purifying respirator, comprising:a face-pieceto cover at least the mouth or nose of a wearer; a pump unit to supplyambient air to the face-piece via an air passage; decontaminating meansfor filtering the ambient air supplied to the face-piece; a demand valveassociated with the face-piece or pump unit and responsive to a wearer∝sdemand for air to deliver supplied air to the wearer; and datacollection means for enabling the volume of air passing through thedecontaminating means to be determined.
 2. A powered air-purifyingrespirator according to claim 1, including a data port to enable thedata collected by the data collection means to be uploaded to a remotecomputer system.
 3. A powered air-purifying respirator according toclaim 1, wherein on-board power is provided to the respirator byrechargeable batteries, the battery voltage is measured on board, and analarm signal is sent to the wearer in advance of discharge.
 4. Acombination of a management system for monitoring an analyzingoperational data from at least one powered air-purifying respirator andat least one powered air-purifying respirator, each respiratorcomprising a face-piece to cover at least the mouth and nose of awearer; a pump unit to supply ambient air to the face-piece via an airpassage; decontaminating means for filtering ambient air supplied to theface-piece; and a demand valve associated with the face-piece or pumpunit and responsive to a wearer's demand for air to deliver supplied airto the wearer;wherein the management system includes data collectionmeans associated with each respirator to enable the volume of air drawnthrough the decontaminating means of the respirator to be determined;and an electronic data processing apparatus into which the datacollected by the data collection means is uploaded for analysis.
 5. Acombination according to claim 4, wherein the data processing apparatusis at least partly situated on-board each respirator in order to enablewarnings to be given to the wearers at appropriate times.
 6. Acombination according to claim 5, wherein the management system includesa remote computer system which contains at least part of the dataprocessing apparatus, the remote computer system being configured to logthe identities of each respirator, or some or all of the component partsof each respirator.
 7. A combination according to claim 6, whereinidentification marks are associated with each respirator, or with someor each component of each respirator, and wherein the remote computersystem is configured to log the identification marks into a database. 8.A powered air purifying respirator, comprising:a face-piece to cover atleast the mouth or nose of a wearer; a pump to supply ambient air to theface-piece via an air passage; decontaminating means for filtering theambient air supplied to the face-piece; a demand valve associated withthe face-piece or pump and responsive to a wearer's demand for air todeliver supplied air to the wearer; a flow meter to measure theinstantaneous flow of air within the respirator; and a clock operable toproduce data which, in conjunction with instantaneous flow data from theflow meter, enables the accumulated volume of air drawn through thedecontaminating means to be determined.
 9. A powered air-purifyingrespirator according to claim 8, wherein the flow meter is situated inthe air passage coupled between the pump and the face-piece.
 10. Apowered air purifying respirator, comprising:a face-piece to cover atleast the mouth or nose of a wearer; a pump to supply ambient air to theface-piece via an air passage; decontaminating means for filtering theambient air supplied to the face-piece; a demand valve associated withthe face-piece or pump and responsive to a wearer's demand for air todeliver supplied air to the wearer; and data collection means forenabling the volume of air passing through the decontaminating means tobe determined on-board the respirator.
 11. A powered air purifyingrespirator according to claim 10, wherein an alarm is provided to thewearer when the useful life of the decontaminating means nears the end.